An unusual case of cardiomegaly.

A 64-year-old woman presented to the emergency department because of progressive fatigue and weight loss for the previous 3 months. She had a 10 pack-year history of smoking with no other significant medical history. Physical examination was unremarkable with normal cardiac and pulmonary auscultation. Her electrocardiogram showed sinus rhythm with very low voltages in all leads (Figure 1A). A chest x-ray film showed enlargement of the cardiac silhouette with normal pulmonary vascularization (Figure 1B). A trans-thoracic echocardiography was performed that revealed an homogeneous mass next to the right side of the heart without clear infiltration and moderate pericardial effusion (Figure 1C; see Movies I through III in the online-only Data Supplement). A contrast-enhanced full-body computed tomography showed a 12 × 8 cm soft-tissue density mass with some necrotic areas in the anterior and medium mediastinum (Figure 1D). No clear pericardial infiltration or involvement was noted, but small pleural and pericardial effusion was present. To better characterize the tumor, a cardiac magnetic resonance was performed , showing an 11 × 8.5 cm intrapericardial mass, with well-defined borders and no signs of pericardial or myocardial infiltration. Partial right atrium and superior vena cava compression was noted, without significant hemodynamic disturbance. T1-weighted fast spin-echo sequence showed multiple hyperintense subcentimetric areas that were hypointense in T2-weighted sequences. There were likely fibrous hypoin-tense septa in both T1-and T2-weighted images (Figure 1E through 1G; see Movies IV and V in the online-only Data Supplement). Initial differential diagnosis was lymphoma, ter-atoma, or thymoma. A computed tomography–guided biopsy was made, and the histological examination confirmed the diagnosis of a cortical subtype (World Health Organization type B1) thymoma (Figure 1H). A combined chemotherapy treatment (cisplatin, doxorubicin, and cyclophosphamide) was initiated with no significant response. The patient developed recurrent pericardial effusion and pericardial tamponade, so a surgical approach was undertaken. Surgery was consistent with diagnosis of intrapericardial tumor with no pericardial or myocardial infiltration observed (Figure 2A). Partial resec-tion of the mass was performed. A control cardiac magnetic resonance 2 months after surgery showed a 48 × 32 mm tumoral mass posterior to the main pulmonary artery, consistent with a nonexcised tumor. No other tumoral component was depicted (Figure 2B through 2F). The patient remains asymptomatic after 4 months of follow-up. Thymoma and thymic carcinomas are rare epithelial tumors, mainly detected in anterior or anterosuperior mediastinum. Clinical findings vary from asymptomatic patients (50% of the cases) to compression of adjacent …